Physiological changes in hybrid Brachiaria cv. Mulato II after accelerated aging to overcome dormancy

Abstract

-To evaluate the effect of accelerated aging to overcome dormancy of hybrid Brachiaria cv. Mulato II (U. brizantha x U. decumbens x U. ruziziensis), seeds were collected from two lots with and without scarification, submitted to 42 °C and high humidity (98%) for different periods (0, 24, 48, 72 and 96 h) and then dried at 30 °C to the humidity of 9.1%. The physiological changes were evaluated by tetrazolium, germination, electrical conductivity, respiratory activity and enzymatic evaluation. The exposure of the hybrid Brachiaria cv. Mulato II to accelerated aging at 42 °C and 98% relative air humidity for up to 96 hours does not alter its viability by the tetrazolium test. Accelerated aging at 42 °C and 98% of humidity for up to 48 hours favors the germination of the scarified seeds of hybrid Brachiaria cv. Mulato II, with increased expression of α-amylase enzyme and reduction of electrical conductivity values. Loss of vigor occurs in scarified seeds of hybrid Brachiaria cv. Mulato II when exposed to accelerated aging at 42 °C and 98% of humidity from 96 hours with consequent changes in enzymatic systems and increased of the respiratory rate. o C e 98% de umidade relativa do ar a partir de 96 h, com consequentes alterações nos sistemas enzimáticos e aumento da taxa respiratória.Termos para indexação: sementes de forrageira, germinação, condutividade elétrica, respiração, isoenzimas.

A newly discovered ageing-repair bacterium,Pseudomonas geniculata, isolated from rescuegrass (Bromus cartharticusVahl) promotes the germination and seedling growth of aged seeds

“…Filho and Usberti (2008) found that the artificially ageing at 40 and 50℃ with 7.6 to 10.8% moisture contents revealed positive effects on seed dormancy releasing in Brachiaria brizantha. Pereira et al (2017) further pointed out that the accelerated ageing up to 48 h can overcome seed dormancy of hybrid Brachiaria cv. Mulato II which is related to increased expression of the α-amylase enzyme, reduction of electrical conductivity values and the changes of antioxidant enzymes, after that, the seed vigor gradually declined from 96 h. Consistently, in the present study the SOD activity was the highest and the MDA content was the lowest in C4, which suggested that the dormancy was partly eliminated by the artificially ageing treatment.…”

Doses and Sources of Nitrogen in Two Forage Cultivars on the Dry Season

“…Mulato II; a tetraploid hybrid, that the result of three generations of crosses and selection (Teixeira et al, 2018). This species, compared to the Marandu forage, has been identified as a plant that stands out for its productivity, adaptability and ability to tolerate diseases and pests that attack other species of the genus Brachiaria (Ramos and Vital, 2016;Pereira et al, 2017). Thus, it is important to study the response of this plant to nitrogen fertilization in periods of prolonged drought, when compared to the most used species of the genus Brachiaria (Teixeira, 2016).…”